There have been two separate releases of Alien Vendetta. The second release, made in 2002 when it was selected for usage on Compet-n, made various changes to almost all of the levels; the biggest change is the replacement of MAP25: Valley of Echoes with another map, MAP24: Clandestine Complex, as well as the relocation of the former MAP24: Demonic Hordes to MAP25.

On August 1, 2016, the expansion Alien Vendetta: Black Label (avbl_v1.wad) was released on the megawad's website, coinciding with a revamp of the site's design. The wad features two new levels that replace MAP01 and MAP02, designed to then-modern level design standards by Brad Spencer (Vorpal). It must be loaded alongside Alien Vendetta to play. On September 27, 2016, the original 2001 version was rereleased on the website as well.

To play it on versions of ZDoom older than 2.3.0, or ZDoom-derived ports with an old codebase, you have to set the compatibility options to "find shortest textures like Doom" (rather than like Boom) for MAP07: Showdown and to "self-referencing sectors don't block shots" for MAP15: Bulls on Parade. The current versions of ZDoom and GZDoom apply the appropriate compatibility options automatically.